Y86 is a simplified x86-like instruction set.
8 user-accessible registers:
EAX ECX EDX EBX ESP EBP ESI EDI
4 states:
AOK HLT ADR INS
Instructions:
halt nop rr/cmovXX irmovl rmmovl mrmovl OPTl jXX call ret pushl popl
ASM file example:
# Execution begins at address 0
.pos 0
init: irmovl Stack, %esp # Set up stack pointer
irmovl Stack, �p # Set up base pointer
call Main # Execute main program
halt # Terminate program
# Array of 4 elements
.align 4
array: .long 0xd
.long 0xc0
.long 0xb00
.long 0xa000
Main: pushl �p
rrmovl %esp,�p
irmovl $4,�x
pushl �x # Push 4
irmovl array,�x
pushl �x # Push array
call Sum # Sum(array, 4)
rrmovl �p,%esp
popl �p
ret
#/* $begin sum-ys 0 */
# int Sum(int *Start, int Count)
Sum: pushl �p
rrmovl %esp,�p
mrmovl 8(�p),�x # ecx = Start
mrmovl 12(�p),�x # edx = Count
xorl �x,�x # sum = 0
andl �x,�x # Set condition codes
je End
Loop: mrmovl (�x),%esi # get *Start
addl %esi,�x # add to sum
irmovl $4,�x
addl �x,�x # Start
irmovl $-1,�x
addl �x,�x # Count--
jne Loop # Stop when 0
End: rrmovl �p,%esp
popl �p
ret
#/* $end sum-ys 0 */
# The stack starts here and grows to lower addresses
.pos 0x100
Stack:
For more details: Chapter 4 of CSAPP
This is a 'lab' (homework) in SE101/ICS (Introduction to Computer Systems).
The original version is a 'pure' simulator, but I made a JIT compiler.
Build:
cc -m32 -o y86sim y86sim.c (tested under Clang 3.2 )
Run:
y86sim file.bin [max_steps]
The 'max' version looks like the normal one, but there is no step counting and non-static error detecting in it.
It could execute most cases correctly and run (almost) as fast as native x86. But, it could not pass the ICS lab tests.
This is also a 'lab' in SE101/ICS.
The implementation is based on the original framework in the course.
Build:
cc -m32 -o y86asm y86asm.c (tested under Clang 3.2 )
Run:
y86asm [-v] file.ys
-v print the readable output to screen.
The simulator is released under WTFPL. Keep calm and have fun with it :) Feel free to send issues and PR to me.
The assembler and the lab tests are not released under any license, so they can be used in education purpose only.
To SE101 students: DO NOT CHEAT! The code is stored in the anti-cheating code base. You know.